System and method for detecting and displaying wind shear

ABSTRACT

A computer based method of detecting and displaying rotational wind shear. Radial wind velocities within first and second adjacent gate sweeps produced by a radar system are detected in a predetermined geographic area, and are compared at points of equal radial distance from the radar system. The radial location of gate to gate wind shear at positions between the radar system and the boundary of the radar systems range are identified and compared to a predetermined threshold wind velocity value to determine the location of high priority gate to gate wind shear. The high priority gate to gate wind shear is then graphically displayed relative to its geographic location on a graphical representation of the predetermined geographic area. A computer based system for detecting and displaying rotational wind shear is also disclosed.

BACKGROUND OF THE INVENTION

This invention relates generally to weather broadcasting and displaysystems, and more particularly to a method for detecting and displayingareas of dangerous wind shear that may result in tornadic activity.

BRIEF DESCRIPTION OF THE PRIOR ART

For many years people have relied on weather broadcasts to help plantheir lives. According to Robert Henson in his book, TelevisionWeathercasting: A History, weather "consistently ranks as the top drawin both local and national news (when featured in the latter)."According to a poll conducted by the National Oceanic and AtmosphericAdministration in 1980, weather was "the major reason that people watchthe news programs."

The field of meteorology has seen significant technological advances inthe past few years. New and innovative devices such as Doppler radar,thunderstorm detectors, and wind and temperature profiles have allhelped meteorologists better understand and predict weather. However,despite the advances in ways to measure meteorological activity, thetelevision broadcast of this information has seen few advances. Thetypical current weathercast display represents the weather symbolicallyrather than realistically and usually only shows the general airtemperature and the location of precipitation. In some instances, asuperimposed satellite display of fluffy cloud patterns is shown movingalong over the flat map from an exaggerated height observation point.The "blue screen" display behind the announcer still usually shows thefamiliar two-dimensional patchwork rainfall amounts in red, yellow,green and blue. The satellite imagery displayed on the evening broadcastmay be anywhere from a half-hour to four hours old.

Also significant is the information that is absent from the conventionalweathercast display, such as: (1) the type of precipitation, (2) thestrength and location of wind shear, (3) the presence of tornadicsignatures showing rapid circular motion, (4) the location of updraftvault, (5) the location of wall clouds, (6) the location of heavylightning activity, and (7) the wind direction on the ground.

The National Weather Service has a network of advanced S-Band radarstations in place at 138 sites in the United States, and is capable ofdelivering 77 different products to government meteorologists. Theseproducts include; winds aloft, lightning activity and wind shearconditions, such as microburst activity. However, of these 77 products,only 11 are commercially available through contract with several privateweather service companies which act as intermediaries between theNational Weather Service and the public. These companies charge for theuse of these eleven products and, in order to receive the latest radar(NEXRAD) information from a particular site, a private individual orcompany pays a monthly fee to receive the radar signal.

There are several patents, which disclose various system utilizing windshear information to detect microburst and wake turbulence.

Albo et al., U.S. Pat. No. 5,648,782 discloses a fuzzy logic processingsystem to detect atmospheric microburst events. The purpose of the Albopatent is to identify microburst activity, which is usually undectableto the human eye, as opposed to tornadic or storm gust fronts which areperceptible without aid of instrumentation.

Gordon, U.S. Pat. No. 5,262,773 discloses a method and apparatus fordetecting specialized meteorological conditions such as microbursts andwake turbulence generated by aircraft. The system is used by flightcontrollers to observe the severity of wind conditions in closeproximity to aircraft runway, to assist with takeoffs and landings.

The present invention is distinguished over the prior art in general,and these patents in particular, by providing a weather-casting systemfor detecting wind shear and determining the possibility of dangeroustwisting winds, so that potentially hazardous weather conditions can beidentified and broadcast to television viewers in real time. The presentinvention will identify microburst activity, but is more particularlydirected toward the formation of circular wind activity that mayindicate a tornado, and the present invention relates to broadcastingthis information to television viewers.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide acomputerized method of detecting and displaying dangerous wind shearwherein wind velocities are detected by a weather radar, and thevelocities are processed to determine the location of wind shearexceeding a predetermined threshold value. The wind shear locations arethen graphically displayed and may be broadcast in connection with atelevision weather cast.

It is a further object of this invention to provide a means forprioritizing which wind shear locations are graphically displayed byexamining ancillary conditions such as the location of additional windshear, the proximity of the wind shear to a storm cell, and theatmospheric conditions above and below the wind shear location.

It is another object of this invention to provide a weather displaysystem capable of displaying the location of dangerous wind shear. Thesystem comprises a weather radar useful for measuring wind velocitiesand data processing means for analyzing the wind velocities anddetermining the existence and location of wind shear exceeding apredetermined value. The data processing means may also prioritize thewind shear locations based upon user-defined conditions, and graphicallydisplay only the high priority wind shear.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a radar station having a central processing unitconfigured for use with the present invention;

FIG. 2 is a block diagram illustrating the basic stages of the presentinvention for collecting and displaying weather data.

FIG. 3 is a graphical representation of wind shear as measured by aradar of the present invention;

FIG. 4 is representative of a method for graphically displaying windvelocities measured from a typical weather radar;

FIG. 5 is an illustration of the output from the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention utilizes a Doppler radar station to detect radarechos and produce signals that are representative of atmospheric andmeteorological phenomena. Referring to FIG. 1, a wind velocity detectionapparatus 20 is shown, having a radar system 22 and a processing unit24. Radar system 22 is any conventional radar emitting and detectionsystem that is capable of measuring wind velocities and includingantenna 26 which is continuously rotated by drive mechanism 30. Thepreferred radar systems are X-band or C-band Doppler radar currentlyused by many television stations across the U.S. The basic operation ofthe radar system 22 is well known to those of skill in the art.

Processing unit 24 is operably connected with the radar system 22 bycommunication leads 32. Processing unit 24 may be configured to vary thebeam width and gate sweep of radar system 22 because processing unit 24governs the operation of radar system 22. The gate sweepProcessing >unit 24 is connected to display 34 for the graphicalpresentation of radar-derived information and to data base 25 foraccessing geographic data stored in database 25 and preferablycorresponding to the predetermined geographic area or coverage area 50(FIG. 3) of radar system 22.

In operation, radar system 22 emits radio signals 36 and, in turn,receives corresponding reflected signals 38 that represent atmosphericconditions such as storm activity and wind velocities. The reflectedsignals 38 are received at antenna 26, converted to electrical pulses orsignals that represent the reflected signals 38, and transferred toprocessing unit 24 along communication leads 32. Processing unit 24produces a radial image of the reflected signals 38 representing theatmospheric conditions. The method for processing the weather data iswell known to those of skill in the art.

FIG. 3 is a graphical representation of the type of radial informationproduced from radar system 22 in combination with processor 24. Thecircle 50 represents the coverage area of the radar system 22. The twoslices of the circle, 52 and 52' represent two gate sweeps of the radar.The gate sweeps are further divided into grid block elements 54 by theprocessor 24. For each grid block element 54, the processor assigns awind velocity value based upon the information received from the radarsystem 22. The radar is only capable of measuring the speed of windcoming towards the radar and moving away from the radar, it does notmeasure wind movement perpendicular to the path of the radar beam. Forexample the wind velocity of two side-by-side grid blocks are opposite(one towards the radar and one away from the radar) this is known aswind shear. In FIG. 3 wind shear is illustrated by the measurement ofopposite wind velocities in grid block elements 54' and 54".

FIG. 4. depicts a conventional radial velocity image 40 derived from theradar system 22 data. The radar screen depicts the grid block elements42 created by the processor 24. Each grid block element 42 is assigned acolor based upon the velocity data calculated for that block. Thecircled area 46 indicates an area of both positive and negative windvelocities relative to the radar, and the grid block elements identifiedas 44 indicate a high gate-to-gate wind shear.

Referring now to FIG. 2, a block diagram of the method embodied in thepresent invention is shown. The first step 110 is using a radar systemto obtain radial wind velocities for a pre-selected geographic region.This step of the method is set forth in the preceding paragraphs, and iswell known to those of skill in the art.

The second step 120 is identifying the location of gate-to-gate windshear of a predetermined threshold value. In this step the processor 24is programmed to identify those areas of wind shear that have a totalvelocity difference above a predetermined value. For example, if athreshold value of 40 knots, the preferred embodiment, is selected, thesystem will identify any area in which the difference between the windvelocity of one grid block and the adjacent grid block equals or exceeds40 knots. The presence of such wind shear provides an early indicationof possible tornadic activity. This step can be further refined byproducing a measurement of derivative wind velocity values. A secondwind velocity screen similar to that illustrated in FIG. 4 may beprepared by measuring the gate to gate derivative wind velocities. Thiswill help illustrate areas that have multiple sites of wind shear, whichare of more concern, and perhaps eliminate the isolated incidents ofwind shear. The user may also be allowed to set up the derivative screento display the derivative wind velocities of several grid blocks in arow, to further refine this step of the process.

The next step 130 is prioritizing the wind shear locations based uponadditional conditions. If the system merely marked all incidence of windshear, the final display screen would typically show hundreds of windshear marks for a given geographic location. Experience has shown thatnot all wind shear events are significant to the weather viewing public.The primary purpose of the wind shear determination is to locatepotential areas of tornadic, storm wall, or microburst activity. Toprioritize the areas of high wind shear, several other conditions areconsidered. First, the presence of multiple wind shear locations issignificant, particularly adjacent wind shear which indicates that windsare swirling in a counterclockwise direction. In the NorthernHemisphere, tornadoes generally twist counterclockwise (obviously, ifthe system were used in the Southern Hemisphere, it should be modifiedto indicate clockwise rotation). Next, the wind shear's proximity to astorm cell is significant, as dangerous wind twisting or micro burstsrarely occur apart from a storm cell. The familiar hook signature of ameso-cyclic activity of a storm would also be very significant. Finally,the wind conditions above and below the identified wind shear should bedetected to determine the depth of the wind shear or circular movement.If the wind shear is isolated in one level of the atmosphere, it is lesslikely to develop into a dangerous twisting situation than windshearwhich is spread through multiple levels. Other conditioning factors maybe added by the user to identify the important incidence of wind shearto be displayed to the viewer.

The final step 140 is graphically displaying the location of theprioritized wind shear, such as the by using "shear markers." Shearmarkers are animated swirling circles which are a trademark of BaronServices, Inc. A graphical representation 64 of the geographic areacovered by the radar system 22 will be necessary so that viewers mayreadily identify the location of the dangerous wind shear. In addition,the wind shear markers are preferably displayed in conduction with thetypical storm cell information, so that the viewers can see where thedangerous swirling winds are in relation to a given storm. An example ofthe graphic representation 64 is shown in FIG. 5. FIG. 5 shows the shearmarkers 60 displayed in three-dimensional perspective, along with athree-dimensional representation of a storm cell 62 which is a recentinnovation in weather-casting. Both are shown here positioned on agraphical representation 64 of the predetermined geographic area coveredby radar system 22. However, one of skill will readily recognize thatthe shear markers are equally useful in the more familiartwo-dimensional format.

While the invention has been described in detail, it is to be expresslyunderstood that it will be apparent to persons skilled in the relevantart that the invention may be modified without departing from the spiritof the invention. Various changes of form, design or arrangement may bemade to the invention without departing from the spirit and scope of theinvention. Therefore, the above mentioned description is to beconsidered exemplary, rather than limiting, and the true scope of theinvention is that defined in the following claims.

We claim:
 1. A computer based method of detecting and displayingrotational wind shear, said method comprising the steps of:a) detectingradial wind velocities within first and second adjacent gate sweepsproduced by a radar system positioned in a predetermined geographicarea; b) comparing said radial wind velocities within said first gatesweep to adjacent said radial wind velocities within said second gatesweep at points of equal radial distance from said radar system; c)identifying the radial location of gate to gate wind shear between saidradar system and the boundary of said radar system's range; d) comparingthe identified gate to gate wind shear to a predetermined threshold windvelocity value to determine the location of high velocity gate to gatewind shear; and e) graphically displaying the geographic location of thehigh velocity gate to gate wind shear relative to a geographicrepresentation of the predetermined geographic area in graphical form.2. The method of claim 1 wherein said detecting step comprises the stepof receiving retrieved radar signals with a single radar.
 3. The methodof claim 1 wherein said detecting step comprises the step of receivingreflected radar signals indicative of a storm cell, and wherein step e)includes the step of displaying a graphical representation of said stormcell.
 4. The method of claim 1 wherein said gate to gate wind shearcomprises winds circumferentially adjacent one another traveling inopposite radial directions, and wherein said comparing step includes thestep of calculating the difference in velocity between said adjacentwinds.
 5. The method of claim 1 wherein said gate to gate wind shearcomprises winds circumferentially adjacent one another and traveling inthe same radial direction at different velocities, and wherein saidcomparing step includes the step of calculating the velocity differencebetween said adjacent winds.
 6. The method of claim 1 further comprisingthe step of calculating the gate to gate derivative wind velocities todetermine the presence of multiple sites of gate to gate wind shear. 7.The method of claim 6 further comprising the step of displaying the gateto gate derivative wind velocities.
 8. The method of claim 7 whereinstep d) comprises the step of prioritizing the gate to gate wind shearbased upon one or more user defined conditions.
 9. The method of claim 8comprising the step of repeating steps a)-d) for multiple levels of theatmosphere above and below the identified gate to gate wind shear.
 10. Acomputer based system for detecting and displaying rotational windshear, said system comprising:a) a radar system including an antennaehaving a circumferential coverage area, said antennae positioned in apredetermined geographic area to detect radial wind velocities withinits coverage area; b) a database including geographic data correspondingto and representative of the predetermined geographic area; c) a centralprocessing unit communicating with said radar system to receiveinformation therefrom corresponding to the radial wind velocities, saidcentral processing unit instructed to divide the circumferentialcoverage area into a plurality of adjacent gate sweeps and to compareradial wind velocities detected in one of said plurality of gate sweepswith radial wind velocities detected in an adjacent gate sweep atlocations radially equidistant from said radar system to determine thelocation of gate to gate wind shear, said central processing unitconfigured to compare the determined gate to gate wind shear with apredetermined threshold value to identify the high velocity gate to gatewind shear and to communicate with said database to associate the highvelocity gate to gate wind shear with the geographic data; and d) adisplay device communicating with said central processing unit tographically depict the high velocity gate to gate wind shear togetherwith the geographic data to provide an indication of the location of thehigh velocity gate to gate wind shear within the predeterminedgeographic area.
 11. The computer based system of claim 10 wherein saidradar system comprises a single dopplar weather radar selected from thegroup consisting of C-band or X-band doppler weather radar.
 12. Thecomputer based system of claim 10 wherein the predetermined thresholdvalue comprises 40 knots, and wherein said central processing unit isfurther configured to further prioritize said high velocity gate to gatewind shear based upon user selected conditions.
 13. The computer basedsystem of claim 12 wherein said user defined conditions comprise thedirection of swirl of the wind.
 14. The computer based system of claim12 wherein said radar system is configured to detect the location of astorm cell, and wherein said user defined condition comprises theproximity of the high velocity gate to gate wind shear to the stormcell.
 15. A computer based method for the detection and graphic displayof atmospheric conditions indicative of tornadoes, said methodcomprising the steps of:a) receiving reflected signals from a radaroperating in a predetermined geographic area, said reflected signalsincluding radial wind velocity data for a plurality of adjacent radargate sweeps; b) comparing the received radial wind velocity data offirst and second adjacent gate sweeps at points of common radialdistance from said radar to identify locations where there exists adifference in velocities; c) processing the radial wind velocity dataassociated with the locations identified in said comparing step toidentify regions where the difference between the radial wind velocitydata of the first and second adjacent gate sweeps exceeds apredetermined threshold value indicative of tornadic activity, saidregions comprising high velocity twisting winds; d) combining agraphical representation of said high velocity twisting winds withstored geographic data representative of the predetermined geographicdata; and e) displaying the product of said combining step in graphicalform on a display device.
 16. The method of claim 15 wherein saidreceiving step comprises the step of detecting said reflected signalswith a single radar.
 17. The method of claim 16 wherein said receivingstep further comprises the step of receiving reflected signalsindicative of a storm cell, and wherein said displaying step includesthe step of depicting the storm cell together with the product of saidcombining step.
 18. The method of claim 15 wherein said gate to gatewind shear comprises winds circumferentially adjacent one another andtraveling in opposite radial directions, and wherein said processingstep comprises the step of calculating the velocity difference betweensaid adjacent winds.
 19. The method of claim 15 wherein said gate togate wind shear comprises wind circumferentially adjacent one anothertraveling in the same radial direction at different velocities, andwherein said processing step comprises calculating the velocitydifference between said adjacent winds.
 20. The method of claim 15further comprising the step of calculating the gate to gate derivativewind velocities to determine the presence of multiple sites of highvelocity twisting winds.
 21. The method of claim 20 further comprisingthe step of displaying the gate to gate derivative wind velocities usingshear markers.
 22. The method of claim 21 wherein said processing stepcomprises the step of prioritizing the gate to gate derivative windvelocities based upon one or more user defined conditions.
 23. Themethod of claim 15 further comprises the step of repeating steps a)-d)for multiple levels of the atmosphere above and below the high velocitytwisting winds.